For me personally, I notice staying hydrated enough and taking as many breaks as I need to helps a lot! Take your time with it, also wishing you luck with your new job :)

For me, when things trigger my Mast Cell Activation Syndrome (MCAS), my POTS symptoms get worse. Stress is a known trigger for MCAS and I can imagine a job would be stressful. Perhaps you could try working on stress reduction techniques like yoga, meditation, journaling, a daily walk in sunshine, etc. That stuff helps me a ton when I do them more regularly!